Automatic and semiautomatic telephone exchange system



Aug; 7, 1945f G. DEAKIN AUTOMATIC AND SEMI*AUTOMATIC TELEPHONE EXCHANGE SYSTEM Filed Feb. 12, 1944 INVENToR. GPZ DFK//Y GENT Patented Aug. 7, 1945 AUTOMATIC AND sEMIAU'roMA'rrc 'rELErHoNEl EXCHANGE `SYSTEM Gerald Deakin,

NewYork, N. `Y., assignor Ito Inv ternational Standard Electric Corporation,

New

.York N. Y., a corporation of Delaware 2, 1944, Serial No. 522,064

Application February 1 5 Claims.

This invention relates to new and useful improvements in class vof service identifying arrangements for telephone systems.

The object of the invention is promptly to identify the class of service to which the calling line is entitled without interfering with other customary operations, such as calling line identication and metering.

With this object in view, the service to which a line is entitled is indicated by a characteristic potential, e. g. a negative D.C. potential, of certain voltage, applied to a contact, e. g. a test contact individual to the line. By means, such as identification iinders, electronic discharge devices may be connected witnthe contact. The discharge devices will variably respond, depending on the potential existingV on the contact, and will thus convey the required information.

The drawing is a diagrammatic illustration of as much of a telephone exchange system as is l necessary for a clear understanding of the invention. For further details of the system, reference should be had to my co-pending applications, Serial No.484,184, filed April 23, 1943, and Serial No. 491,628, filed June 21, 1943, and the applcations and patents mentioned therein.

It is assumed that in the absence of a special identication signal, theregister will operate in the normalway to control the establishment of a connection, as describedin said co-pending applications.

The class of service to which the calling line is entitled, is indicatedby a distinguishing potential -S, which is applied over a relatively high (e. g. 10,000 ohms) resistance rs to the t or test wire of a subscribers line under the control of the 'customary cut-off relayCOR of the line. The test wire is, of course, multipled tothe terminal banks of line finders and final selector switches. This potential will remain on the t wire during conversation. However, on account of the high resistance of rs, the line may be identied by applying to the t wire a positive potential, in the manner disclosed in my co-pending applications. Such a positive identification potential is placed momentarily on the t wire through a 'relatively low resistance, thereby destroying the effect of the permanently connected service identification potential -S.

The -S potentials may be -26 to -64 volts, the different classes of service being distinguished by a spacing of 2 volts from an adjacent class. The calling line number identification potentials are also spaced from one another by 2 volts and, since they are positive, they may include -some of the voltages used for class of service identification.

In addition to the above characteristic potentials, each line has a characteristic -N and -C potential applied to its t wire over a back or a front contact' of the line relay LR and a back contact of COR. Depending on the units digit of the line, the -N potential may be from -2 to -20 volts. The -C potential may be -22 volts and, when applied to the t wire, indicates that the line is calling.

When a call is initiated, the first finder connects with the line and causes the energization of COR over the control wire c. COR will disconnectthe t wire from the armature of line relay Lr and connect it with the -S source of potential over resistance 1s. The call is extended from the first finder to a B link where a metering relay MR. is connected with the t wire over a gas valve GV. An identification relay GSR, common to a group of lines, is connected over a resistance r and a positively poled rectifier S with the t wire in the line nder or link circuit associated with the `first line finder. The gas valve GV breaks down-to permit the operation of the metering relay MR only when negative potential of 80 volts is applied to the t wire. This is the booster metering potential. Thus, the normally connected relatively low -S potential will not cause energize.- tion -of the metering relay.

As described in my co-pending application,

. Serialv No. 491,628, the register or a toll operators position is provided with a string of triode circuits for the purpose of identifying the number of` the calling line. In the presentcase, these circuits are used for scanning the service classiiication, there being as many pairs of triodes and associated gas valves as there are service classes to be identified. i

vWhen a common lead X leading to the valve circuits, is connected under the control of `the register or an operators key over rst and second identification finders, iirst line finder and second line finder, with the t wire of the calling line, one pair of class identification triodes V1, V2; V3, V4 etc., Will operate. As explained in my co-pending application, Serial No. 491,628, only that pair of triodes operates to the grids of which the same potentials are connected. In the present case, V1 and V2 will operate (V4 having S2 potential applied to its grid), cause the momentary lighting of the associated gas valve GV and the energization of GVR and GSR.

The class of service to which the calling line is entitled is thus identified and may then be recorded or indicated in any well-known manner.

No -S potential is placed on the t wires of unrestricted main lines and therefore the register or the operator would not receive the special signal that other lines would give.

What is claimed is:

l. In a telephone exchange system, a plurality cf subscribers lines each comprising a pair of talking conductors and a test conductor, a central exchange, means for extending said lines to said exchange, a source of D. C. potentials lfrom which are derived potentials characteristic of different classes of service, means for applying to the test conductors of calling lines a D. C. potential characteristic of the class of service to which said linesare entitled, an electronic discharge device at said exchange for each class of service, a relay associated with each discharge device and arranged to operate only when two D. C. potentials applied to respective electrodes of said device bear a predetermined relationship, means at said exchange for connecting t an electrode of each of said devices a diiferent D. C. potential characteristic of each class of service and means for extending the test conductor of a calling line in multiple to another electrode of each of said devices.

2. In a telephone exchange system, subscribers line circuitameans including automatic switches for connecting a calling lineto a called line, one of said switches having terminals for a group of lines, a source of D. C. potentials from which are derivedcharacteristic class of service potentials, means for applying to terminals of calling lines the class of service D. C. potential to which they are entitled, an electronic discharge device for each class of service, means for applying a dif ferentv characteristic D. C. potential identifying the different classes of service to the different devices, switching means for connecting said devices with a terminal of the calling line, and means connected with each discharge device so arranged that it operates only, when the potentials applied to the associated devices bear a predetermined relationshipl to one another.

3. In a telephone exchange system, subscribers line circuits, means including automatic switches for connecting a calling lineto a called line, one of said switches havingA terminals for a group of lines, a source of D. C. potentials from which are derived characteristic class of service potentials, I

means for applying to terminals of calling lines the class of service potential to which they are entitled, a plurality of pairs of multi-electrode discharge devices, a different characteristic p0- tential identifying the different classes of service being applied to the grid of the first device in each pair, switching means for Yconnecting the grids of all the second devices with the terminal of the calling line t0 which the class of service potential is applied, and means connected with each pair of discharge devices and so arranged that it operates only when the potentials applied to the grids of both devices associated therewith bear a predetermined relationship to one another.

4. In a telephone exchange system, subscribers line circuits, means including automaticswitches for connecting a calling line to a called line, one of said switches having talking and test terminals for a group of lines, a source of D. C. potentials from which are derived a characteristic class of service potential and a characteristic number identifying potential assigned to each line, and a certain potential designating the calling condition of a line, means for applying all said potentials tothe test terminal of the line, the calling potential upon the initiation of a call on a line, the number identifying potential while the line is idle and the class of service potential when the calling line has been connected, a plurality of pairs of triodes, a 'different' characteristic potential identifying the different classes of service being applied to the grid of the rst triodein each pair, switching means for connecting the grids of the second triodes withv the test terminal of the calling line, and means connected with each pair of triodes so arranged that it operates only when the potentials applied to the grids of both tubes associated therewith `bear a predetermined relationship to one another. I

5. Ina telephone exchange system, subscribers' line circuits, means including automaticswitches for connecting a calling lineto a called line, one of said switches having'talking and test terminals for a group of lines, va line and a cut-off relay for each line, a source of D. C. potentials from which are derived a cha'racter'istieclass of service potential anda characteristic number identifying potential assigned toeach line, and a certain potential designating lthe calling condition of a line, all said potentialsfbeing applied to the test terminal of the line, the calling potential over a front contact of rthe line relay and a baci; contact of the cut-off relay,the number identifying potential over back contacts of the=line and cut-otr relays and the class of service potential over a front contact of the cut-off relay, a plurality of pairs of triodes, 'one pair for eachclass 0f service, a diiferent characteristic potential identifying the different classes of service being applied to the grid of the first triode in each pair,'switching means for connecting the grids of all the second triodes in parallel with `the test terminal of the calling line, and a gas. valve connected with each pair of triodes overa circuitso arranged that the gas valve operates only whenthe same potentials are applied to the grids of both'tubes associated therewith. I YGERALD DEAKIN. 

